It’s possible that that’s the idea, with a TV the idea is that it’s fixed unlike your phone, iPad, or even Mac that can be moved around. With that being said, the AppleTV 4K has always been capable of gyroscopic and accelerometer interpretation as I think you may be forgetting that this is what is used in the remote for gaming. I would imagine they would use that same capability to communicate with the AirPods. I can’t imagine it will be quite as efficient without having the W1 or H1 chip for better communication but it also only has to interpret the movement of just the AirPods instead of both the AirPods and the device. Furthermore, this may also be a key feature implemented or improved to be presented on the next-gen AppleTV rumored to be completed earlier this year and released soon. Could even be another reason for them waiting to release it.